Recording instrument



June 1, 1937.

J. H. HAGENGUTH ET AL RECORDING INSTRUMENT Filed Oct. 18, 1934 f (v5 Red 14' l4 AA AV 55 1! V V -0 c I 45 49 L Green 15' Cascaded oscil'ogmph Inventor-s:

Julius H. liagencguth 69 William A. Mc Morris,

y eh Attorl eg.

Patented June 1, 1937 UNITED STATES PATENT orrlcr.

ris, Pittsfield, Mass.,

assignors to General Electric Company, a corporation of New York Application October 18,

4 Claims.

Our invention relates to improvements in recording instruments and concerns particularly devices designed to be placed in operation upon the occurrence of the events, the character of 5 which is to be recorded.

In order to record the conditions in an electrical transmission system as a result of a stroke of lightning or other transient phenomena, it is necessary to provide apparatus which will begin m to record within an extremely short period of time as such phenomena frequently have a duration of only a few microseconds and the resulting disturbance often lasts for only a portion of a cycle of a commercial frequency alternating current. For practical reasons, the recording apparatus should be arranged to be set in operation upon the occurrence of a disturbance to be recorded and to have its operation stopped after the disturbance is over, rather than being arranged for continuous operation. The consumption of record film or strip would otherwise be prohibitive.

Our primary object, accordingly, is to provide recording apparatus in which the operation is initiated in response to and within an extremely short interval after the beginning of a disturbance to be recorded. Our object is to provide recording apparatus suitable for laboratory study of phenomena in various electrical circuits as well as for field study of electrical transmission and communication systems.

Another object is to provide a recording device of the type employing a light source as the record-producing medium in which a greatly increased speed of initiation of the light source is obtained.

Still another object isthe provision of recording apparatus in which mechanical motion and thermal and mechanical inertia are eliminated in the initiation of the recording operation.

Other and further objects and advantages will become apparent as the description proceeds.

In carrying out our invention in its preferred form, we employ a source of cold light, such as a point-source or neon crater lamp in conjunction with a deflecting mirror, movable photographic film, and the usual appurtenances of a photographic recording oscillograph. In addition, means, preferably non-mechanical, are provided for energizing the light source in response to a disturbance which is to be recorded. Owing to the absence of thermal inertia in a source of cold light, and the elimination of mechanically moving parts from the lamp connecting arrangement, the lamp can be made to come up to full brilliancy and initiate the record 1934, Serial No. 748,970

within an interval of the order of a few microseconds.

The features of our invention which we believe to be novel and patentable will be pointed out in the claims appended hereto. Our invention will be better understood by referring to the following description taken in connection with the accompanying drawing which is a schematic diagram of one embodiment of our invention showing the electrical circuit.

Referring now more in detail to the drawing, an electrical circuit or system in which transients are to be recorded is shown at H. The apparatus is described as used with an alternating circuit but it will be understood that the invention is equally applicable to direct current circuits. An oscillograph element 12 is provided which may be of the deflecting light-beam type, well known in the art, carrying a mirror l3 deflecting in response to variations in the quantity to be measured. If the current in the circuit II is the quantity to be recorded, a current transformer l4 may be provided for inductively connecting the element l2 to the circuit II. A rotating drum I5 carrying a photographic film IS on its surface, a film-driving motor II, and a light source l8 are also provided. It may befound convenient to provide also a mirror IQ for changing the path of the light beam produced by source I8. It will be understood that all of the optical parts of the apparatus are to be enclosed in a light-tight box (not shown) arranged to protect the film l6 against outside light or any light from source l8 other than the beam 20 controlled by the deflecting mirror l3. The optical arrangement may be similar to that employed in oscillographs well known in the art.

For the light source 18,. however, we employ a lamp producing .what is commonly known as cold light, and which does not depend on heating the elements of the lamp to incandescence to obtain light. A type of lamp which we have found satisfactory for the purpose is a neon crater or point-source glow lamp of the type disclosed in certain patents to D. McF. Moore, e. g., Patents No. 1,900,577 and No. 1,900,578, granted March 7, 1933, but it will be understood that our invention is not limited thereto. Such a lamp consists of a cathode 2| containing a. sharp cavity or crater 22-, a tubular anode 23 surrounding the cathode, and anenclosing envelope 24 containing a suitable gas, such as neon. The gas pressure is such, approximately to 40 millimeters of mercury, that a glow discharge will form in the hole or sharp depression 22 in the cathode 2|. Controlling means, which will be described more in detail hereinafter, are provided for causing the lamp l5 to become illuminated immediately after the occurrence of a dis- 5 turbance in circuit II, and preferably also for shutting down the apparatus after a record has been taken on the film I5. I A current source 25 is provided to supply energy for illuminating the lamp l8 and also for 10 operating the auxiliary apparatus. The source 25 is shown as an alternating current source for the sake of illustration, but it will be understood that the apparatus may be energized directly by a direct-current source. gized by the current source 25, and a rectifier tube 21 energized by transformer 25 are provided for furnishing a high potential direct-current to the cold-light source |8. For controlling the lamp |8, a grid-controlled discharge tube or electric valve 28 is connected in series with the lamp I8. Preferably also a reactance 28 is connected in series, and condensers 30 and 3| are connected in shunt with the direct-current source ta smooth out fluctuations in the voltage applied to the lamp l8. A resistor 32 of relatively high resistance may be connected in shunt with the lamp l8, and a current-limiting resistor 34 may be connected in series with the lamp. A resister 33, a relay winding 53 and a condenser 54 in parallel are included in the lamp circuit for reasons which will be explained later.

For the purpose of initiating the operation of the apparatus by causing the lamp l8 to become illuminated, a device is provided for ignitthe occurrence of a disturbance to be recorded. The discharge tube 28 preferably includes a control grid 35, an anode 35, and a cathode 31. A current transformer 38 may be provided with a primary winding connected in series with circuit II and a secondary winding connected between the cathode 31 and the control grid of the tube 28 to control the grid potential of tube 35 in response to disturbances in the circuit 45 To make the apparatus instantly and equally responsive to impulses of either polarity in the circuit H, a pair of rectlfiers or a full-wave rectifier 33 is preferably interposed between the transformer 38 and the electrodes of the control tube 28. The full-wave rectifier 38 may take the form of a discharge tube having a pair of anodes 40 and a cathode or a pair of connected cathodes 4 I.

If desired, a potentiometer 42 may be provided, connected at one end to a tap 43 brought out from the secondary winding of the transformer 38 and at the other end to the cathodes 4| of the rectifier 39, the anodes 40 of the rectifier 39 being connected to the ends of the secondary winding of the transformer 35. An adjustable tap 44 on the potentiometer 42 is connected to the grid 35 of discharge tube 28 to adjust the sensitivity of the apparatus.

A potentiometer 45 with a tap 45 is connected across the direct-current source formed by transformer 25 and rectifier 21. The potentiometer tap 48 is connected to the cathode 31 of discharge tube 28 to bias the tube 28 to its non-conducting condition except when a potential is developed in potentiometer 42 as a result of a disturbance in the circuit I.

In order to guard against the appearance of excessive voltages in the secondary winding of the transformer 35 in response to current im- 7 pulses in the circuit M, an element 41 having a A transformer 25. enering the lamp-controlling discharge tube 28 upon conductance increasing with voltage may be connected between the anodes 4|] of rectifier 38. The resistance element 41 may, for example, be of the type disclosed in United States Patent No. 1,822,742 to McEachron, composed of a mixture of silicon carbide and carbon with a suitable hinder or silicon carbide mixed with other conducting materials such as tungsten, molybdenum, and the like. To prevent the apparatus from acquiring floating potentials, the midtap 43 of the transformer 38 is connected to ground through a resistor 48 and the negative side of the directcurrent source formed by transformer 25 and rectifier 21 is also grounded through a conductor 49. A condenser 50 may also be connected between the grid 35 of control tube 28 and ground to counterbalance the inherent capacity coupling between the grid 35 and the anode 35 which might tend to raise the potential of the grid and fire the tube when voltage is suddenly applied to the anode by closing the switch contacts 55 and 55. A push-button switch 5| may be provided for manually initiating the illumination of the lamp l8 for trial purposes.

For the purpose of shutting down the apparatus after a record is obtained, a time delay relay 52 of any suitable type is provided having a winding 53 connected in series with the lamp l8. A condenser 54 is also shunted across the winding 53 to compensate for the inductance of the winding 53 in order that there will be no delay in the initiation of current flow in lamp i8. The resistor 33 serves to damp out any oscillations which might be set up in the circuit formed by the inductive winding 53 and the condenser 54. The relay 52 comprises also a movable arm 55 carrying a pair of insulated contacts 55 and 51, a spring 58 biasing the movable contacts 55 and 51 to their right-hand position, a pivoted detent 59 for holding the contacts 55 and 51 in the left- -hand position and adapted to be released by energization of winding 53, a pair of stationary contacts 50 cooperating with movable contact 58, and two pairs of stationary contacts 5| and 52 cooperating with the movable contact 51. The relay 52 is of the time delay type, but for the sake of clarity the arrangement for delaying its response to the flow of current in winding 53 is omitted from the diagrammatic showing in the drawing. The contacts 50 are in the circuit of the lamp |8 controlling its energization. Suitable indications or alarms, such as, respectively, green and red lamps, 53 and 54, are provided for indicating whether the apparatus is properly set for recording a disturbance, or a record has already been made. The contacts 5| of relay 52, are in a circuit from the current source 25 to the motor l1 andthe green lamp 53, and the contacts 52 are in a circuit from the current source 25 to the red lamp 54.

The cathodes of the discharge tubes 21, 23, and 39 may be indirectly heated by filaments or may, themselves, constitute filaments connected to suitable current sources, such as additional secondary windings (omitted from the drawing to avoid confusion) in the transformer 25, in a manner well understood by those skilled in the art.

In order to prepare the apparatus for recording a disturbance, a fresh photographic film is first mounted at IS on the drum l5 and the movable arm 55 of the relay 52 is then placed in the position shown with circuits closed through the contacts 58 and 5|. The circuit closed through contacts 8| starts the motor l1 and lights the itiation of a disturbance in the circuit ll.

green light 63 to indicate that the apparatus is in readiness for taking a record. While the apparatus is held in readiness for producing a rec- 0rd, the filaments of the discharge tubes 21, 25, and 39 are left continuously connected to their supply sources and the film-driving motor I1 is left running continuously. Upon the occurrence oi! a disturbance resulting in a current exceeding a predetermined value in the circuit II, a voltage is induced in the transformer 38 of sufllcient magnitude to overcome the negative grid bias provided by the potentiometer 45, and the controlling tube 28 is caused to become conducting. As the grid is connected to the transformer 38 through the full-wave rectifier 39, the potential oi the grid 35 is raised regardless of the polarity at any instant of the current in the circuit ll. Thereupon a direct-current circuit is completed from the rectifier 21, through the reactance 29, a conductor 85, the contacts 55 and 50, the resistor 34, the relay winding 53, the crater lamp It, the lamp-controlling discharge tube 28, a conductor 85, the left-hand portion of the potentiometer 45, and a conductor 51, back to the grounded negative side of the direct-current source formed by a center tap 68 on transformer 26.

Since there are no mechanically moving parts and no' parts which must be heated after. a'disturbance occurs, mechanical and thermal inertia are eliminated and the lamp l8 acquires Iull brilliancy virtually instantaneously upon the in- The oscillograph element, being continuously connected, follows the current in circuit il continuously and produces an oscillogram on the film It by controlling the light beam 20 produced by the source of cold light l5. During normal current variations in the circuit ll, of course, no record is produced since the lampfli is then dark.

A predetermined time after the initiation of the light source l8, it is extinguished, the apparatus is shut down, and a signal or alarm is given to warn the operator that a newfilm'should be inserted and the apparatus should be reset for another record. This is accomplished by means or the time delay relay 52 connected in series with the lamp l5. Alter the predetermined time interval, the relay 52 trips,- contacts 55 and 5! are opened, and the contacts 82 are closed. Thecircuit through the lamp I5 is broken at 50, extinguishing the lamp, and the circuit to the motor H, and the green signa. lamp 52 is broken at 6|, stopping the motor and-extinguishing the green signal lamp. The closing of a circuit through the red signal lamp 5!, however, provides a warning to the operator to reset the apparatus. The signal lamps 53 and 54 may, of course, be located at a place convenient for the operator, regardless of the, remoteness oi the recorder. The time delay of relay 52, the speed of motor l1, and the peripheral length of the film II are such as to provide a recording period ample for obtaining a complete record 01 any anticipated transient.

separate oscillographs connected in cascade. For example, a second recording apparatus 59 of the type Just described responsive to additional transformers l4 and 38' may also be set for operation with the exception that it remains without power supply until a supply circuit is closed to it through conductors 25 upon the shutting down of the first apparatus and the closing of contacts 52.

.We have herein shown and particularly described certain embodiments of our invention and certain methods or operation embraced therein for the purpose of explaining its principle and showing its application, but it will be obvious to those skilled in the art that many modifications and variations are possible and we aim, therefore, to cover all such modifications and variations as fall within the scope of our 1 invention which is defined in the appended claims.

What we claim as new and desire to secure by Letters Patent 0! the United States is:

1. In a device of the light-beam type for recording transients in an electrical system, a" cold light producing lamp for supplying a beam of light substantially instantly upon energization of the lamp, a source of current for energizing said lamp, controlling means responsive to voltage impulses ior connecting said lamp to its current source, and means for impressing voltage impulses of a given polarity upon said controlling means in response to transients of either polarity in the electrical system.

2. Transient recording apparatus comprising normally inactive first and second osciilographs each arranged for recording transients occurring on a given electrical circuit, means responsive to transients occurring. on said circuit for initiating the operation of the oscillographs, and means for initially preventing operation of the second oscillograph and responsive to a recording operation of said first oscillograph, for stopping operation 01 the first oscillograph after a time delay and conditioning the second oscillograph for operation.

3. In a light-beam type recorder for an electrical system, a cold light producing lamp as the light-beam source, a source of current for energizing said lamp, an electric valve in series with said lamp and said current source, said valve having a control electrode, and full-wave rectifler means with an input circuit and with an output circuit connected to said control electrode, said input circuit being connected in responsive relation to the electrical system.

4. In a transient recorder of the light-beam type, a lamp for producing a deflectible beam, 9. source of current for energizing said lamp, an electric valve for closing a circuit through said lamp to initiate a record, a resistor, a relay including contacts and having a contact-opening winding connected in shunt with said resistor, and a condenser also connected in shunt with said resistor, said lamp source, valve, resistor, and relay contacts being in series.

JULIUS H. HAGENGUTH. WILLIAM A. McMORRIS. 

